4G is synonymous with Long Term Evolution (LTE) technology, which is an evolution of the existing 3G wireless standard. LTE is an advanced form of 3G that implements a shift from hybrid data and voice networks to a data-only IP network. There are two key technologies that enable LTE to achieve higher data throughput than predecessor 3G networks: multiple input, multiple output (MIMO) and Orthogonal frequency-division multiplexing (OFDM). OFDM is a transmission technique that uses a large number of closely-spaced carriers that are modulated with low data rates. It's a spectral efficiency scheme that enables high data rates and permits multiple users to share a common channel. The MIMO technique further improves data throughput and spectral efficiency by using multiple antennas at the transmitter and receiver. It uses complex digital signal processing to set up multiple data streams on the same channel. The early LTE networks support 2×2 MIMO (indicates two antennas at the transmit end and 2 antennas at the receive end) in both the downlink and uplink.
5G is the term used to describe the next-generation of mobile networks beyond the 4G LTE mobile networks of today. Most experts say 5G will feature network speeds of 20 G/bps or higher and have a latency of mere milliseconds. Not only will people be connected to each other but so will machines, automobiles, city infrastructure, public safety and more. 5G will likely be designed to build upon the existing LTE networks and many features will start to be available as part of the LTE-Advanced Pro standard. Some of those features include carrier aggregation, which lets operators use existing spectrum more effectively and also increases network capacity. Carrier aggregation will also allow wireless operators to increase user throughput rates. Software-defined networking (SDN) and network functions virtualization (NFV) are play a key role for operators as they migrate from 4G to 5G and scale their networks. SDN will be necessary for operators to carve virtual “sub-networks” or slices that can be then used for bigger bandwidth applications. That includes video, which might need throughput speeds of 10 Gb/s as well as lower bandwidth applications to connect devices that are less demanding on the network, such as smartwatches. 5G networks are also expected to have always-on capabilities and be energy efficient, all of which will likely require new protocols and access technologies.
Throughput, latency, reliability, availability are paramount importance with the increasing diversity of services carried by mobile networks. 5G systems are expected to be built in a way to enable logical network slices, which will allow telecom operators to provide networks on an as-a-service basis. Through the use of SDN and NFV, functional nodes can be created at various points in the network and access to the functional nodes can be restricted to sets of devices. Network slicing technology can provide connectivity for a variety user devices including smart meters requiring high availability and high reliability data-only service, with a given latency, data rate and security level and, at the same time, providing connectivity for applications requiring very high throughput, high data speeds and low latency such as an augmented reality service.
Slice handover/reselection is the process where a UE is served by a first slice, but then is moved to another slice to receive network services. A UE may move from a first slice to a second slice (a slice handover, or a slice reselection) for a number of reasons. For example, if a user is attached to a first slice, and moves to a location that is not served by resources in the slice there is a need to transfer the user to a different slice to continue supporting the UE. Service requirement changes may be another reason for a slice handover. For example, it may be desirable to switch from a network slice with low mobility support when the UE is in a congested areas to high mobility support when the UE may be travelling at high speed on a highway.
Due to the diversity of 5G application scenarios, new mobility management schemes are greatly needed to guarantee seamless handover in network slicing based 5G systems. There is a need to provide intelligent decision making in the allocation and switching of network slices. There is a need to provide scalable expansion of network resources according to subscriber traffic and service delivery. There is a need to provide on demand resource allocation in 5G networks using slice allocation. There is a need for a user equipment initiated method to dynamically allocate and switch network slices accessed by the user equipment. There is a need for instantiating carrier aggregation slices comprising both 4G RRC and 5G RRC to comply with user plane service level agreements. There is also a need to provide service assurance based on needs, device priority and service priority.